1795P China ARCHES: A multicenter phase III randomized double-blind placebo (PBO)-controlled efficacy and safety trial of enzalutamide (ENZA) + androgen deprivation therapy (ADT) vs PBO + ADT in Chinese patients (pts) with metastatic hormone-sensitive prostate cancer (mHSPC)
Authors: F. Zhou, Z. Gongqian, H. Guo, Z. Hu, X. Zhang, D. He, Z. He, D. Zhang, Y. Li, H. Kadeerbai, Y. Liu, D. Ye
Journal: Annals of Oncology (2023)

In the global ARCHES trial (NCT02677896), ENZA + ADT improved overall survival and radiographic progression-free survival (rPFS) vs PBO + ADT in pts with mHSPC. The China ARCHES trial evaluated the efficacy and safety of ENZA + ADT vs PBO + ADT in Chinese pts with mHSPC. Chinese men with mHSPC (positive bone scan or CT scan) were randomized 2:1 to ENZA (160 mg/day) + ADT or PBO + ADT, stratified by disease volume and prior docetaxel therapy. Treatment continued until intolerability or confirmed radiographic progression. The primary endpoint was time to prostate-specific antigen (PSA) progression (TTPP; PSA progression defined as ≥25% increase and absolute increase of ≥2 ng/mL above the nadir, confirmed after ≥3 weeks), based on central laboratory test. Selected secondary endpoints included rPFS, time to castration resistance (TTCR), PSA undetectable (<0.2 ng/mL) rate in patients with detectable PSA at baseline, and safety. We report the results of a prespecified interim analysis (63 TTPP events accrued). At data cut-off (November 18, 2022), 180 pts (ENZA + ADT, n=120; PBO + ADT, n=60) had been randomized from 27 centers in China (median age, 68.5 years). Baseline characteristics were balanced between treatment arms. Median treatment duration with ENZA + ADT vs PBO + ADT was 25.66 vs 15.11 months. Based on 63 centrally confirmed PSA progressions (ENZA + ADT, 23; PBO + ADT, 40), ENZA + ADT significantly reduced the risk of PSA progression by 87% vs PBO + ADT (Table). rPFS, TTCR, and PSA undetectable rate were among the secondary endpoints improved with ENZA + ADT vs PBO + ADT. Safety outcomes in pts from China were consistent with those in the global ARCHES population.Table: 1795PEndpointENZA + ADT N=120PBO + ADT N=60Hazard ratioa (95% CI)p valueTTPPb (95% CI)cNR (NR, NR)9.2 (6.54, 17.48)0.13 (0.076, 0.222)<0.0001drPFSb (95% CI)cNR (28.25, NR)19.4 (13.63, NR)0.33 (0.196, 0.556)<0.0001d,eTTCRb (95% CI)cNR (31.18, NR)8.3 (6.41, 14.69)0.172 (0.107, 0.276)<0.0001d,ePSA undetectable, % (95% CI)f76.3 (67.4, 83.8)22.8 (12.7, 35.8)<0.0001e,gaCox proportional hazards modelh bMedian months: Kaplan-Meier method cBrookmeyer and Crowley method dLog-rank testh eNominal p value fClopper-Pearson method based on exact binomial distribution gCochran-Mantel-Haenszel score testh hStratified model/test CI=confidence interval; N=no. of randomized pts; NR=not reached. Open table in a new tab aCox proportional hazards modelh bMedian months: Kaplan-Meier method cBrookmeyer and Crowley method dLog-rank testh eNominal p value fClopper-Pearson method based on exact binomial distribution gCochran-Mantel-Haenszel score testh hStratified model/test CI=confidence interval; N=no. of randomized pts; NR=not reached. Efficacy and safety results in China ARCHES were generally consistent with those in the global ARCHES trial.